Low individualized growth hormone (GH) dose increased renal and cardiac growth in young adults with childhood onset GH deficiency

Abstract

Objective: In childhood onset GH deficiency (GHD) a reduction in left ventricular mass (LV-mass) and impairment of systolic function as well an impairment in glomerular filtration rate (GFR) has been shown. The aim of the present study was to assess if a low GH dose resulted in an improvement in morphological and functional parameters of these organs.

Design and patients: Eleven patients with childhood onset GHD were investigated before and after 10 months of GH treatment at a dose of 1.5 IU/day (range 1-2), corresponding to 0.02 IU/kg/day or 7 microg/ kg/day. The GH dose resulted in a serum IGF-I level in the normal range in all but one patient.

Measurements: Doppler echocardiography of the heart and ultrasound examination of the kidneys was performed. Glomerular filtration rate (GFR) was estimated with iohexol clearance and urinary proteinuria was measured with 24-h urinary samples collected for analyses of albumin, alpha-1-microglobulin, IgG and albumin/creatinine clearance ratio. Body composition was measured by bioelectric impedance analysis.

Results: L V-mass index increased significantly after GH treatment (P = 0.04), and there was a clear trend for a positive correlation between the increase in serum IGF-I and the increase in LV-mass index, although it did not reach significance (r= 0.57, P = 0.07). GH treatment did not increase cardiac fractional shortening. Kidney length increased significantly (P = 0.02) with an average increase of 1 cm (range - 0.5-1.5 cm). No significant changes in median GFR or serum creatinine were recorded. Three patients with subnormal GFR before GH treatment normalized after 10 months of treatment. Urine analysis showed no abnormalities before or after GH treatment. A significant decrease in percentage fat mass was recorded (P = 0.03).

Conclusion: A low individualized GH dose to adults with childhood onset GHD resulted in an increase in LV-mass index and kidney length. Re-establishing GH treatment with a low dose in this patient group can lead to a further somatic maturation of these organs, probably not accomplished previously.